Linked Questions
26 questions linked to/from Why is CBC with predictable IV considered insecure against chosen-plaintext attack?
0
votes
2answers
114 views
Is CTR more secure than CBC?
In cryptography, a block cipher mode of operation is an algorithm that uses a block cipher to provide information security such as confidentiality or authenticity. A block cipher by itself is only ...
32
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2answers
8k views
7zip : Why does encrypting the same file with AES-256 not give the same output?
Using 7-zip 19.00, on Windows 10 1909, build 18363.592, I encrypted a text file with the contents "hello there" using AES-256 and the password "123". I did this two times, the exact same procedure, ...
2
votes
2answers
631 views
using different IV and SALT with AES-CBC but same KEY
I'm working on this project where a client can send a message, now obviously sending it in plainText is not very smart. So I decided to Encrypt it with AES-CBC.
Now, each time I encrypt something, ...
3
votes
1answer
203 views
Best practices for IV generation
What are the best practices for IV generation for AES and other algorithms?
Is RNG enough?
What if I cannot use RNG and need to use a variable that is related to some characteristic of the ...
10
votes
1answer
1k views
Which block cipher parameters should be kept secret?
Which of the parameters of a block cipher (e.g., algorithm name, mode of operation, IV (if any), key length) are essential to keep secret?
3
votes
2answers
136 views
Why BouncyCastleAesCbcBytesEncryptor is using a salt and an initialization vector?
I'm using the class BouncyCastleAesCbcBytesEncryptor from Spring Security. One of the constructor has the following signature:
...
0
votes
2answers
96 views
Randomly initialised global counter used to encrypt the kth message with $\operatorname{IV} = \operatorname{IV} + k \hspace{5mm} mod \hspace{5mm} 2^n$ [duplicate]
The use of an increasing IV is not secure for a block cipher. That is, using a random IV for the first message then $\operatorname{IV} + 1$ for the second , $\operatorname{IV}+ 2$ for the 3rd etc. How ...
0
votes
2answers
726 views
Is it required to use a random IV for AES-CBC with random key per message? [duplicate]
I'm developing a program to encrypt and decrypt a file with AES-256/CBC in Java. And I want it to be safe enough. In my case, I generated random AES key for each file to encrypt and decrypt them.
My ...
1
vote
1answer
732 views
Is it safe to send IV in plain text for every request?
Currently, I am creating a project with an IoT device. This is an offline device which shows a QR code which can be scanned by a mobile device, which sends this code to a server. The server handles ...
1
vote
1answer
1k views
Simulation of Chosen Plaintext Attack on CBC, Predictable IV with OpenSSL
I would like to simulate the CBC IV attack where the IV is predictable.
It's described in the answer to this question:
chosen plaintext attack on CBC, predictable iv
(Only "Yes" and "No" are valid ...
-5
votes
1answer
207 views
at rest encrypton question from someone who knows nothing
this forum is way above me and the members here are far, far smarter than I am, so this probaby isn't the place to ask such a simple question, but whatever.
All I wanted to ask is for at rest ...
2
votes
1answer
296 views
Attack on AES-CBC with small pool of IV
Let's assume that for encryption with AES in CBC mode we have $IV\in \{0\}^{113}||\{0,1\}^{15}$.
I know that if we can predict next IV with 100% probability there is attack that completely breaks ...
1
vote
1answer
1k views
Question about IV/initialization vectors
I found some code to get crypto-js to encrypt data in the browser, and with a pointer from someone on SO, it now decodes data as well.
My next question is about the use of an IV; is an IV like a salt ...
3
votes
1answer
179 views
BEAST Attack: from guessing to decoding
I understood the XOR trick that allows an attacker to guess a block of a previously sent message from the client to the server: the attacker forces the client to send the message $\tilde{m} = c_n \...
8
votes
2answers
1k views
CBC variant: why encrypt the nonce with a different key?
I am a newbie at cryptography. I understand the CBC encryption, somewhat. You don't want to use the same "IV" for every message because then the ciphers are not very random. My question is regarding ...